• One big absence from the lineup is senior Pat Colwell (.300, 45 R, 15 RBI), a three-year starter who was the team’s top defensive outfielder last season. Colwell will redshirt as he continues to recover from a severe calf injury suffered in a JetSki accident over the summer. O’Sullivan will miss the first two games against Oklahoma as punishment for an unspecified violation of team rules.

• Castro has graduated, but the Aztecs appear solid behind the plate with junior Matt Parker. The Rancho Bernardo High grad handled 252 chances without an error last season. Wilson, a sophomore from Cathedral Catholic, also should see plenty of action as the backup catcher.

• Freshman right-hander Bryan Crabb gets the start in the first game of tomorrow’s doubleheader against Oklahoma. It is Crabb’s first collegiate start, although he is well-acquainted with the mound at Tony Gwynn Stadium. Crabb was the winning pitcher for Coronado two years ago in the CIF Division IV finals. His father Gregg is familiar with the mound as well, having pitched for the Aztecs in 1981-82.

• SDSU’s 56-game regular-season schedule includes 38 home games (and two others across town at USD), so the Aztecs have an opportunity to make something of their home field advantage. Highlights for the home schedule include four-game series against Oklahoma and Santa Clara, two games against the Toreros and single contests against highly regarded Kentucky, Fresno State, Cal State Fullerton, UC Irvine and Long Beach State. Mountain West Conference teams who visit are Utah, New Mexico, Air Force and UNLV. In addition, SDSU will host the MWC Tournament. The six-team, double-elimination tourney is scheduled for May 25-29 and will determine which team receives the conference’s automatic berth in the NCAA Tournament.

— KIRK KENNEY

San Diego State opens the 2010 baseball season at home tonight against No. 22-ranked Oklahoma. SDSU coach Tony Gwynn, never one given to exaggeration, estimates that he already has been asked one question “a gazillion times.”

What’s it like without Stephen Strasburg?

“The answer is: tougher,” Gwynn said. “A lot tougher.”

Strasburg’s exploits were well-chronicled last season. In sum, he went 13-1 with a 1.32 ERA, 195 strikeouts and 19 walks in 109 innings. He was the national College Player of the Year. He was the first overall player selected in the major league draft. He signed a record $15.1 million contract with the Washington Nationals.

It likely will be a long time before another pitcher like Strasburg comes along here. So the question isn’t so much how you replace him but how you move on without him.

“There’s no Strasburg out there, so it’s like, ‘Who’s gonna be the guy?’ ” said Gwynn, who begins his eighth season as Aztecs coach. “That’s a good question. Until we actually play somebody, we aren’t going to know who’s going to be the guy.”

It’s a particularly difficult question for SDSU this season because in addition to Strasburg the Aztecs also lost their other two weekend starters — Tyler Lavigne and Jon Berger — as well as seven other pitchers.

In fact, only two pitchers return who started a game for the Aztecs last season, sophomore right-hander Ryan O’Sullivan (11 starts) and junior left-hander Craig Rasmussen (two).

In addition, longtime pitching coach Rusty Filter also departed, for a similar position at Stanford. Filter has been replaced by Eric Valenzuela, who moved across town from USD after coaching the Toreros pitchers the past six years.

“It’s wide open,” Valenzuela said. “We had individual meetings with our guys to talk about roles, and a lot of the roles are: Be ready to pitch.

“There’s so many games early that they’re going to have to be jack-of-all-trades — long relief, short relief, close.”

The closer’s role is up for grabs because junior right-hander Addison Reed, last year’s national Stopper of the Year, has been moved to the front of the rotation. O’Sullivan is the No. 2 starter. Beyond that the spots are wide open.

Reed is following the same path as Strasburg, who was SDSU’s closer before moving into the rotation as a sophomore. As far as Reed is concerned, that’s where the comparisons should end.

Reed was 20-for-20 in save opportunities last season, employing a fastball that he said topped out at 96 mph.

“I thought that was all right until I saw (Strasburg hit) 102,” said Reed, who is from Rancho Cucamonga. “I’m not going to go out there and try to pump the radar guns to 102. I’m not going to go out there and try to do something I can’t. ... I’m just going to act like I’m closing but going a few more innings.”

Strasburg donated $141,000 from his bonus to have the grass area at Tony Gwynn Stadium behind home plate and along the baselines replaced with synthetic turf.

“Every time we get on that turf it’s a reminder that here’s a guy who came out here without very much fanfare and three years later he was the talk of baseball,” Gwynn said. “I think he taught some people some valuable lessons about work ethic and preparation. I know we’ve got guys who one day would love to be in that same position.

“With our pitching, who knows who is going to be that guy to stand up.”